Stabilization of 1,1,1-trichloroethane

ABSTRACT

THE STABILIZATION OF 1,1,1-TRICHLOROETHANE BY ADMIXING SUCH WITH 0.5 TO 10 WT. PERCENT OF A MIXTURE OF ACETONITRILE. 1.4-DIOXANE AND ETHYLENEDIAMINE.

Int. 01. C07c1 7/42, 19/02 US. Cl. 260-652.5 R 1 Claim ABSTRACT OF THEDISCLOSURE The stabilization of 1,1,l-trichloroethane by admixing suchwith 0.5 to 10 wt. percent of a mixture of acetonitrile, 1,4-dioxane andethylenedia'mine.

This application is a division of application Ser. No. 805,923, filedJan. 5, 1969, now Pat; No. 3,590,088, which in turn is a division ofapplication Ser. No. 609,- 681, filed Jan. 16, 1967, now Pat. No.3,445,532, which in turn is a continuation of application Ser. No.316,772, filed Oct. 16, 1963.

The present invention relates to new and valuable 1,1,1- trichloroethanestabilizer combinations consisting of an organic compound containing atleast one nitrile group and at least one compound of the groupconsisting of amines, 1,4-dioxane, nitromethane and alcohols, and theinvention also includes 1,1,l-trichloroethane incorporating saidcombinations, said 1,1,1-trichloroethane exhibiting improved stability.More particularlythe invention is concernedwith the problem ofminimizing the marked tendency of 1,1,1 trichloroethane to undergodecomposition and relates to a process for minimizing this tendency. I

It is Well known that halogen hydrocarbons such as vinyl chloride,vinylidene chloride, trichloroethaneftrichloroethylene,perchloroethylene, and other aliphatic.

chlorinated hydrocarbons very easily undergo decomposition. Thisdecomposition generally takes place withthe simultaneous formation ofacids and is caused, among other things, by the presence of light, air,or traces of water. It is furthermore known that the splitting ofi ofacid is greatly promoted by the presence of certain metals.

Thus, for example, the decomposition reaction is catalyzed by iron,aluminum, magnesium, such metals.

The decomposition reaction can beso violent in' the case of some ofthese compounds, that'the further use and processing of these halogenhydrocarbons inmetal' vessels is possible only with the greatest ofdifliculty if United States Patent Oflice and the alloys of I at all. Asnoted above, light serves to promotethe decomposition furthercomplicating further use and processing of the halogen hydrocarbons.

This defect is especially marked in the case of 1,1,1- Itrichloroethane, 1,1,l-trichloroethane being more inclined to split offhydrochloric acid and then blacken than any of the above-namedchlorinated hydrocarbons. Theldecomposition reaction can progress to thecomplete resinification of the material and accordingly the usefulnessof,

1,1,1-trichloroethane per se is severely limited. For industrial use,1,1,1-trichloroethane is employed only t0- fore been eifected using forthe stabilization dialkylsulf gether with an added stabilizer. a v

The stabilization of 1,1,1-trichloroethane'has hereto- 3,787,509Patented Jan. 22, 1974 oxides, dialkylsulfites, dialkylsulfides,1,4-dioxanes, epoxides, monoketones, trialkylsilylethers, tetralkylcompounds of tin and lead, nitroalkanes, sec. or tert. alcohols,nitriles, acetylene alcohols, oxazirines, thiazirines, oxaphosphorines,and thiaphosphirines. These known stabilizing agents must usually beused in large quantities in order that there results an adequatestabilizing eflect, so that the 1,1,1-trichloroethane thus stabilizedtakes on the character of a mixture of solvents. The stabilizer1,1,1-trichloroethane mixtures so characterized are suitable only for alimited field of application. Furthermore the use of dioxane and anumber of the other conventionally employed stabilizing compounds isfurthermore undesirable from the standpoint of useful applicationsbecause of their toxicity. Certain of the conventionally usedstabilizers set out above have also proved undesirable due to the colorwhich they impart to the 1,1,1-trichloroethane while others are entirelyunsuitable due to their great chemical reactivity with the agents to betreated whereby they are used up in the reaction and the stabilizingeifect pro duced gradually lost, decomposition thereupon setting in.Still another group of the known stabilizers is characterized by thegroups great sensitivity to hydrolysis in oxygen and therefore thisgroup finds only limited application.

It is one of the objects of the present invention to provide new andvaluable compositions which have proved of value in the stabilization of1,1,l-trichloroethane.

Another object of the present invention is to provide a simple andeifective procedure of stabilizing 1,1,1- trichloroethane.

A further object of the present invention is to provide stabilized1,1,1-trichloroethane containing such stabilizing compositions andespecially 1,l,1-trichloroethane stabilized by a. mixture of an organiccompound containing at least one nitrile group and at least one compoundof the group consisting of amines, 1,4-dioxane, nitromethane, andalcohols.

' "Other objects of the present invention and advantageous featuresthereof will become apparent as the invention proceeds.

It has been found that the stabilization of 1,1,1-trichlomethane isobtained by incorporation in the 1,1,l-trichloroethane of a mixture ofan organic compound having at least one nitrile group with at least onemember of the group consisting of amines, 1,4-dioxane, nitromethane, oralcohols. The stabilizing effect is achieved by the addition to the 1,1,l-trichloroethane of a mixture of an organic compound having at leastone nitrile group and an amine, 1,4-dioxane, nitromethane, or analcohol; however, it has been further found that additional improvementsin the stabilization effect can be achieved by using as stabilizer acombination of the organic nitrile with two stabilizing agents.

Instances of nitriles suitable as components for the stabilizing mixtureinclude for example: acetonitrile, propionitrile, acrylonitrile,B-methoxypropionitrile, dimethylaminoacetonitrile,methylaminopropionitrile, methyleneaminoacetonitrile,dimethylaminopropionitrile, diethylaminoacetonitrile,methylethylaminoacetonitrile, malodinitrile, and thiodipropionitrile, aswell as the monoand polycyanethylated products of acetone,methylethylketone and acetic acid ester.

The amines which have proven especially elfective for use in thestabilizing combinations of the invention are those having more than oneamino group in the molecule. While the monoamines have proved to besatisfactory, the effectiveness of the monoamines in the stabilizingmixtures is far exceeded by diamines, as for instance by ethylenediamineand by other polyamines. Examples of amines suitable for use in thestabilizing of 1,1,1-trichloroethane '3 include: triallylamine,di-n-butylamine, dimethylaniline, triethylamine, n-butylamine,ethylenediamine, etc.

As alcohol components for the stabilizing mixture, there may be used thesaturated and unsaturated primary, secondary, and tertiary alcohols,preferably having up to in the presence of a specific amount of a metalpowder, granules or chips.

The stabilizer compositions of the present invention can be added in thevarious stages of the manufacturing process of 1,1,1-trichloroethane. Incertain instances the carbon atoms per OH group as for example methanol,5 presence of the stabilizing compounds may be especially ethanol,n-propanol, n-butanol, tert. butanol, allyl alcodesirable in the gaseousphase, as for example in the hol, and propargyl alcohol. However, ketonealcohols, distillation thereof. such as for example,4-hydroxybutanone-(2) or S-hy- The following examples serve toillustrate the present droxy-pentanone-(3) and the products of thecondensation 1O invention without, however, limiting the same thereto.of C to C amines with formaldehyde or acetaldehyde In the followingtable, there are given the effect of a can be satisfactorily combinedwith the nitriles to stabilize number of known stabilizers when usedeach by themmethyl chloroform. I selves, and a number of stabilizercombinations in accord- The stabilizer compositions of the presentinvention are ance with the invention in the stabilization of 1,1,l.-triemployed in quantities of about 0.05 to weight percent chloroethane.In each case the stated amount of stabilizer but preferably inquantities of 0.2 to 1 weight percent. An or stabilizer combination and5 grams of aluminum turnaddition of 0.5 weight percent of stabilizingcomposition ings or 5 grams of aluminum granules was added to 100produces a stabilization of methyl chloroform that is adegrams of1,1,l-trichloroethane and the resulting mixture quate for most practicalrequirements. then heated. under reflux until the chlorohydrocarbon Inthe preparation of the stabilizing compositions, the blackened or untilHCl was split olf. The time that elapsed amounts of nitrile, alcohol,amine, etc. are generally emup tothe discoloration point or theevolution of HCl can ployed in equivalent amounts. However, it is alsopossible be taken as a measure of the elfectiveness of the tested toprepare the stabilizing mixture with more or less of substance orcombination of substances as stabilizer for the nitrile compoundbeing'present in relation to the other 1,1,1-trichloroethane. Icomponents, both types of components are, however, re- The examples inthe table have been divided into three quired to be present in order toobtain the desired degree sections: i of stabilization. I (I) Examplesin which no stabilizer is used.

The method of the invention for stabilizing 1,1,1-tri- (II) Examplesemploying for the stabilization of l,1,1- chloroethane is especiallyadvantageous in that the abovetri hloroethane the following knowntabilizers; described stabilizer compositions are considerably more aeffective than any one of the single components by itself (a) Amines incomparable concentration, as a result of which it is (b) 1,4-dioxanepossible to stabilize methyl chloroform with substantially (c)Nitromethane smaller amounts of stabilizer for most general applica- (d)Alcohols tions. 5 (c) Nitriles.

The elfectiveness of any of the stabilizer compositions for a specificpurpose can be determined, for example, by X p employlng for theSiabllllatlon of simply boiling a specific amount of1,1,l-trichloroethane trichloroethane the stabilizer combinations inaccordance with identical percentages of combinations to be evaluatedwith the invention.

Time for splitting Amount off of 1101 or added, to blackening weight ExStabilizer percent Minutes Hours 1 None 2 Trlallylamlne 0.5 3Di-n-butylamine 0.5 4 Dimethylaniline 0.5 5 Trlethylamlne 0.5 6n-Butylamlne 0.5 7 Ethylene diamine 0.5

' jIr b...--- s 1,4-Dloirane 0.5 II-c. 9 Nitromethane... 0.5 II- 10Ethyl alcohol 0.5 11 Allyl alcohol 0.5 12 Propargyl alcohol 0.5 ,1 1,3tart. Butanol L..- 0. 5

II-e l4. Aerylonitrlle 0.5 15 Aeetonitrile 0.5 16 g-Methoxyproplmllttrle0.5 17 lethy1eneaminaeetonitrlle 0.5 18 Dteyanethylatedmethylethylketonekn 0.5 19 Dleyanethylated aeetic'aeid ester 0. 5

,m 20 Acetonltrlle 0.25 20 Ethylenediamine 0.25 21 Ac'eonitrile 0. 25 211,4-dioxane 0.25 22 B-Methoxypropionltrlle". 0.25 22 1,4-d1oxane 0.25 23Acetonltrtle 0.17 '23 1-,4-dloxane;.' 0.17 23 Ethylenediamlne.-- 0.17 24Acetonltrlle 0.25 24 Nitromethane 0.25 25 Acetonitrile 0.25 25 tart.Butane 0.25 26 Aeetonltrlle 0.25 26 Nitromethane 0.25 26 tert.B

27 Aeetonltrile 0.25 27 tert.Butanol; 0.25 21 nln'rana 11.25 28Acetouitrlle 1.0

tart. Butanol..'.. 5.0

See-footnotes at end of table.

TABLE--Continued Time for splitting Amount ofi of H01 or added, toblackening weight Ex. Stabilizer percent Minutes Home TTT 28 lA-rlinxmm29 Acetonitrile 29 Nitromethane. 29 1,4-dioxane 30 Acetonitrile 30 tertButanoL. 30 Nitromethane 1 The stabilization example was conducted inthe presence of 5 grams of aluminum turngs. 2 The stabilization examplewas conducted in the presence of 6 grams of aluminum granules.

UNITED STATES PATENTS 3,008,999 11/1961 Kander 260-6525 R HOWARD T.MARS,

Sims 260-6525 R Cormany et a1. 260-652.5 R Cormany et al. 260-6525 RMissbach 260-6525 Brown 260-6525 Bjllfel 200652.5

Primary Examiner

